/**
 * @author Rich Tibbett / https://github.com/richtr
 * @author mrdoob / http://mrdoob.com/
 * @author Tony Parisi / http://www.tonyparisi.com/
 * @author Takahiro / https://github.com/takahirox
 * @author Don McCurdy / https://www.donmccurdy.com
 */

import {
	AnimationClip,
	Bone,
	Box3,
	BufferAttribute,
	BufferGeometry,
	ClampToEdgeWrapping,
	Color,
	DirectionalLight,
	DoubleSide,
	FileLoader,
	FrontSide,
	Group,
	InterleavedBuffer,
	InterleavedBufferAttribute,
	Interpolant,
	InterpolateDiscrete,
	InterpolateLinear,
	Line,
	LineBasicMaterial,
	LineLoop,
	LineSegments,
	LinearFilter,
	LinearMipmapLinearFilter,
	LinearMipmapNearestFilter,
	Loader,
	LoaderUtils,
	Material,
	MathUtils,
	Matrix4,
	Mesh,
	MeshBasicMaterial,
	MeshPhysicalMaterial,
	MeshStandardMaterial,
	MirroredRepeatWrapping,
	NearestFilter,
	NearestMipmapLinearFilter,
	NearestMipmapNearestFilter,
	NumberKeyframeTrack,
	Object3D,
	OrthographicCamera,
	PerspectiveCamera,
	PointLight,
	Points,
	PointsMaterial,
	PropertyBinding,
	QuaternionKeyframeTrack,
	RGBAFormat,
	RGBFormat,
	RepeatWrapping,
	Skeleton,
	SkinnedMesh,
	Sphere,
	SpotLight,
	TangentSpaceNormalMap,
	TextureLoader,
	TriangleFanDrawMode,
	TriangleStripDrawMode,
	Vector2,
	Vector3,
	VectorKeyframeTrack,
	sRGBEncoding
} from "./three.module";

var GLTFLoader = (function () {

	function GLTFLoader(manager) {

		Loader.call(this, manager);

		this.dracoLoader = null;
		this.ddsLoader = null;

	}

	GLTFLoader.prototype = Object.assign(Object.create(Loader.prototype), {

		constructor: GLTFLoader,

		load: function (url, onLoad, onProgress, onError) {

			var scope = this;

			var resourcePath;

			if (this.resourcePath !== '') {

				resourcePath = this.resourcePath;

			} else if (this.path !== '') {

				resourcePath = this.path;

			} else {

				resourcePath = LoaderUtils.extractUrlBase(url);

			}

			// Tells the LoadingManager to track an extra item, which resolves after
			// the model is fully loaded. This means the count of items loaded will
			// be incorrect, but ensures manager.onLoad() does not fire early.
			scope.manager.itemStart(url);

			var _onError = function (e) {

				if (onError) {

					onError(e);

				} else {

					console.error(e);

				}

				scope.manager.itemError(url);
				scope.manager.itemEnd(url);

			};

			var loader = new FileLoader(scope.manager);

			loader.setPath(this.path);
			loader.setResponseType('arraybuffer');

			if (scope.crossOrigin === 'use-credentials') {

				loader.setWithCredentials(true);

			}

			loader.load(url, function (data) {

				try {

					scope.parse(data, resourcePath, function (gltf) {

						onLoad(gltf);

						scope.manager.itemEnd(url);

					}, _onError);

				} catch (e) {

					_onError(e);

				}

			}, onProgress, _onError);

		},

		setDRACOLoader: function (dracoLoader) {

			this.dracoLoader = dracoLoader;
			return this;

		},

		setDDSLoader: function (ddsLoader) {

			this.ddsLoader = ddsLoader;
			return this;

		},

		parse: function (data, path, onLoad, onError) {

			var content;
			var extensions = {};

			if (typeof data === 'string') {

				content = data;

			} else {

				var magic = LoaderUtils.decodeText(new Uint8Array(data, 0, 4));

				if (magic === BINARY_EXTENSION_HEADER_MAGIC) {

					try {

						extensions[EXTENSIONS.KHR_BINARY_GLTF] = new GLTFBinaryExtension(data);

					} catch (error) {

						if (onError) onError(error);
						return;

					}

					content = extensions[EXTENSIONS.KHR_BINARY_GLTF].content;

				} else {

					content = LoaderUtils.decodeText(new Uint8Array(data));

				}

			}

			var json = JSON.parse(content);

			if (json.asset === undefined || json.asset.version[0] < 2) {

				if (onError) onError(new Error('THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported.'));
				return;

			}

			if (json.extensionsUsed) {

				for (var i = 0; i < json.extensionsUsed.length; ++i) {

					var extensionName = json.extensionsUsed[i];
					var extensionsRequired = json.extensionsRequired || [];

					switch (extensionName) {

						case EXTENSIONS.KHR_LIGHTS_PUNCTUAL:
							extensions[extensionName] = new GLTFLightsExtension(json);
							break;

						case EXTENSIONS.KHR_MATERIALS_CLEARCOAT:
							extensions[extensionName] = new GLTFMaterialsClearcoatExtension();
							break;

						case EXTENSIONS.KHR_MATERIALS_UNLIT:
							extensions[extensionName] = new GLTFMaterialsUnlitExtension();
							break;

						case EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
							extensions[extensionName] = new GLTFMaterialsPbrSpecularGlossinessExtension();
							break;

						case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
							extensions[extensionName] = new GLTFDracoMeshCompressionExtension(json, this.dracoLoader);
							break;

						case EXTENSIONS.MSFT_TEXTURE_DDS:
							extensions[extensionName] = new GLTFTextureDDSExtension(this.ddsLoader);
							break;

						case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
							extensions[extensionName] = new GLTFTextureTransformExtension();
							break;

						case EXTENSIONS.KHR_MESH_QUANTIZATION:
							extensions[extensionName] = new GLTFMeshQuantizationExtension();
							break;

						default:

							if (extensionsRequired.indexOf(extensionName) >= 0) {

								console.warn('THREE.GLTFLoader: Unknown extension "' + extensionName + '".');

							}

					}

				}

			}

			var parser = new GLTFParser(json, extensions, {

				path: path || this.resourcePath || '',
				crossOrigin: this.crossOrigin,
				manager: this.manager

			});

			parser.parse(onLoad, onError);

		}

	});

	/* GLTFREGISTRY */

	function GLTFRegistry() {

		var objects = {};

		return {

			get: function (key) {

				return objects[key];

			},

			add: function (key, object) {

				objects[key] = object;

			},

			remove: function (key) {

				delete objects[key];

			},

			removeAll: function () {

				objects = {};

			}

		};

	}

	/*********************************/
	/********** EXTENSIONS ***********/
	/*********************************/

	var EXTENSIONS = {
		KHR_BINARY_GLTF: 'KHR_binary_glTF',
		KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
		KHR_LIGHTS_PUNCTUAL: 'KHR_lights_punctual',
		KHR_MATERIALS_CLEARCOAT: 'KHR_materials_clearcoat',
		KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
		KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
		KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
		KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
		MSFT_TEXTURE_DDS: 'MSFT_texture_dds'
	};

	/**
	 * DDS Texture Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/MSFT_texture_dds
	 *
	 */
	function GLTFTextureDDSExtension(ddsLoader) {

		if (!ddsLoader) {

			throw new Error('THREE.GLTFLoader: Attempting to load .dds texture without importing DDSLoader');

		}

		this.name = EXTENSIONS.MSFT_TEXTURE_DDS;
		this.ddsLoader = ddsLoader;

	}

	/**
	 * Punctual Lights Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
	 */
	function GLTFLightsExtension(json) {

		this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;

		var extension = (json.extensions && json.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL]) || {};
		this.lightDefs = extension.lights || [];

	}

	GLTFLightsExtension.prototype.loadLight = function (lightIndex) {

		var lightDef = this.lightDefs[lightIndex];
		var lightNode;

		var color = new Color(0xffffff);
		if (lightDef.color !== undefined) color.fromArray(lightDef.color);

		var range = lightDef.range !== undefined ? lightDef.range : 0;

		switch (lightDef.type) {

			case 'directional':
				lightNode = new DirectionalLight(color);
				lightNode.target.position.set(0, 0, - 1);
				lightNode.add(lightNode.target);
				break;

			case 'point':
				lightNode = new PointLight(color);
				lightNode.distance = range;
				break;

			case 'spot':
				lightNode = new SpotLight(color);
				lightNode.distance = range;
				// Handle spotlight properties.
				lightDef.spot = lightDef.spot || {};
				lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0;
				lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0;
				lightNode.angle = lightDef.spot.outerConeAngle;
				lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
				lightNode.target.position.set(0, 0, - 1);
				lightNode.add(lightNode.target);
				break;

			default:
				throw new Error('THREE.GLTFLoader: Unexpected light type, "' + lightDef.type + '".');

		}

		// Some lights (e.g. spot) default to a position other than the origin. Reset the position
		// here, because node-level parsing will only override position if explicitly specified.
		lightNode.position.set(0, 0, 0);

		lightNode.decay = 2;

		if (lightDef.intensity !== undefined) lightNode.intensity = lightDef.intensity;

		lightNode.name = lightDef.name || ('light_' + lightIndex);

		return Promise.resolve(lightNode);

	};

	/**
	 * Unlit Materials Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
	 */
	function GLTFMaterialsUnlitExtension() {

		this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;

	}

	GLTFMaterialsUnlitExtension.prototype.getMaterialType = function () {

		return MeshBasicMaterial;

	};

	GLTFMaterialsUnlitExtension.prototype.extendParams = function (materialParams, materialDef, parser) {

		var pending = [];

		materialParams.color = new Color(1.0, 1.0, 1.0);
		materialParams.opacity = 1.0;

		var metallicRoughness = materialDef.pbrMetallicRoughness;

		if (metallicRoughness) {

			if (Array.isArray(metallicRoughness.baseColorFactor)) {

				var array = metallicRoughness.baseColorFactor;

				materialParams.color.fromArray(array);
				materialParams.opacity = array[3];

			}

			if (metallicRoughness.baseColorTexture !== undefined) {

				pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture));

			}

		}

		return Promise.all(pending);

	};

	/**
	 * Clearcoat Materials Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
	 */
	function GLTFMaterialsClearcoatExtension() {

		this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;

	}

	GLTFMaterialsClearcoatExtension.prototype.getMaterialType = function () {

		return MeshPhysicalMaterial;

	};

	GLTFMaterialsClearcoatExtension.prototype.extendParams = function (materialParams, materialDef, parser) {

		var pending = [];

		var extension = materialDef.extensions[this.name];

		if (extension.clearcoatFactor !== undefined) {

			materialParams.clearcoat = extension.clearcoatFactor;

		}

		if (extension.clearcoatTexture !== undefined) {

			pending.push(parser.assignTexture(materialParams, 'clearcoatMap', extension.clearcoatTexture));

		}

		if (extension.clearcoatRoughnessFactor !== undefined) {

			materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;

		}

		if (extension.clearcoatRoughnessTexture !== undefined) {

			pending.push(parser.assignTexture(materialParams, 'clearcoatRoughnessMap', extension.clearcoatRoughnessTexture));

		}

		if (extension.clearcoatNormalTexture !== undefined) {

			pending.push(parser.assignTexture(materialParams, 'clearcoatNormalMap', extension.clearcoatNormalTexture));

			if (extension.clearcoatNormalTexture.scale !== undefined) {

				var scale = extension.clearcoatNormalTexture.scale;

				materialParams.clearcoatNormalScale = new Vector2(scale, scale);

			}

		}

		return Promise.all(pending);

	};

	/* BINARY EXTENSION */
	var BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
	var BINARY_EXTENSION_HEADER_LENGTH = 12;
	var BINARY_EXTENSION_CHUNK_TYPES = { JSON: 0x4E4F534A, BIN: 0x004E4942 };

	function GLTFBinaryExtension(data) {

		this.name = EXTENSIONS.KHR_BINARY_GLTF;
		this.content = null;
		this.body = null;

		var headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH);

		this.header = {
			magic: LoaderUtils.decodeText(new Uint8Array(data.slice(0, 4))),
			version: headerView.getUint32(4, true),
			length: headerView.getUint32(8, true)
		};

		if (this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC) {

			throw new Error('THREE.GLTFLoader: Unsupported glTF-Binary header.');

		} else if (this.header.version < 2.0) {

			throw new Error('THREE.GLTFLoader: Legacy binary file detected.');

		}

		var chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
		var chunkIndex = 0;

		while (chunkIndex < chunkView.byteLength) {

			var chunkLength = chunkView.getUint32(chunkIndex, true);
			chunkIndex += 4;

			var chunkType = chunkView.getUint32(chunkIndex, true);
			chunkIndex += 4;

			if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {

				var contentArray = new Uint8Array(data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength);
				this.content = LoaderUtils.decodeText(contentArray);

			} else if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN) {

				var byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
				this.body = data.slice(byteOffset, byteOffset + chunkLength);

			}

			// Clients must ignore chunks with unknown types.

			chunkIndex += chunkLength;

		}

		if (this.content === null) {

			throw new Error('THREE.GLTFLoader: JSON content not found.');

		}

	}

	/**
	 * DRACO Mesh Compression Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
	 */
	function GLTFDracoMeshCompressionExtension(json, dracoLoader) {

		if (!dracoLoader) {

			throw new Error('THREE.GLTFLoader: No DRACOLoader instance provided.');

		}

		this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
		this.json = json;
		this.dracoLoader = dracoLoader;
		this.dracoLoader.preload();

	}

	GLTFDracoMeshCompressionExtension.prototype.decodePrimitive = function (primitive, parser) {

		var json = this.json;
		var dracoLoader = this.dracoLoader;
		var bufferViewIndex = primitive.extensions[this.name].bufferView;
		var gltfAttributeMap = primitive.extensions[this.name].attributes;
		var threeAttributeMap = {};
		var attributeNormalizedMap = {};
		var attributeTypeMap = {};

		for (var attributeName in gltfAttributeMap) {

			var threeAttributeName = ATTRIBUTES[attributeName] || attributeName.toLowerCase();

			threeAttributeMap[threeAttributeName] = gltfAttributeMap[attributeName];

		}

		for (attributeName in primitive.attributes) {

			var threeAttributeName = ATTRIBUTES[attributeName] || attributeName.toLowerCase();

			if (gltfAttributeMap[attributeName] !== undefined) {

				var accessorDef = json.accessors[primitive.attributes[attributeName]];
				var componentType = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

				attributeTypeMap[threeAttributeName] = componentType;
				attributeNormalizedMap[threeAttributeName] = accessorDef.normalized === true;

			}

		}

		return parser.getDependency('bufferView', bufferViewIndex).then(function (bufferView) {

			return new Promise(function (resolve) {

				dracoLoader.decodeDracoFile(bufferView, function (geometry) {

					for (var attributeName in geometry.attributes) {

						var attribute = geometry.attributes[attributeName];
						var normalized = attributeNormalizedMap[attributeName];

						if (normalized !== undefined) attribute.normalized = normalized;

					}

					resolve(geometry);

				}, threeAttributeMap, attributeTypeMap);

			});

		});

	};

	/**
	 * Texture Transform Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
	 */
	function GLTFTextureTransformExtension() {

		this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;

	}

	GLTFTextureTransformExtension.prototype.extendTexture = function (texture, transform) {

		texture = texture.clone();

		if (transform.offset !== undefined) {

			texture.offset.fromArray(transform.offset);

		}

		if (transform.rotation !== undefined) {

			texture.rotation = transform.rotation;

		}

		if (transform.scale !== undefined) {

			texture.repeat.fromArray(transform.scale);

		}

		if (transform.texCoord !== undefined) {

			console.warn('THREE.GLTFLoader: Custom UV sets in "' + this.name + '" extension not yet supported.');

		}

		texture.needsUpdate = true;

		return texture;

	};

	/**
	 * Specular-Glossiness Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness
	 */

	/**
	 * A sub class of StandardMaterial with some of the functionality
	 * changed via the `onBeforeCompile` callback
	 * @pailhead
	 */

	function GLTFMeshStandardSGMaterial(params) {

		MeshStandardMaterial.call(this);

		this.isGLTFSpecularGlossinessMaterial = true;

		//various chunks that need replacing
		var specularMapParsFragmentChunk = [
			'#ifdef USE_SPECULARMAP',
			'	uniform sampler2D specularMap;',
			'#endif'
		].join('\n');

		var glossinessMapParsFragmentChunk = [
			'#ifdef USE_GLOSSINESSMAP',
			'	uniform sampler2D glossinessMap;',
			'#endif'
		].join('\n');

		var specularMapFragmentChunk = [
			'vec3 specularFactor = specular;',
			'#ifdef USE_SPECULARMAP',
			'	vec4 texelSpecular = texture2D( specularMap, vUv );',
			'	texelSpecular = sRGBToLinear( texelSpecular );',
			'	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture',
			'	specularFactor *= texelSpecular.rgb;',
			'#endif'
		].join('\n');

		var glossinessMapFragmentChunk = [
			'float glossinessFactor = glossiness;',
			'#ifdef USE_GLOSSINESSMAP',
			'	vec4 texelGlossiness = texture2D( glossinessMap, vUv );',
			'	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture',
			'	glossinessFactor *= texelGlossiness.a;',
			'#endif'
		].join('\n');

		var lightPhysicalFragmentChunk = [
			'PhysicalMaterial material;',
			'material.diffuseColor = diffuseColor.rgb;',
			'vec3 dxy = max( abs( dFdx( geometryNormal ) ), abs( dFdy( geometryNormal ) ) );',
			'float geometryRoughness = max( max( dxy.x, dxy.y ), dxy.z );',
			'material.specularRoughness = max( 1.0 - glossinessFactor, 0.0525 );// 0.0525 corresponds to the base mip of a 256 cubemap.',
			'material.specularRoughness += geometryRoughness;',
			'material.specularRoughness = min( material.specularRoughness, 1.0 );',
			'material.specularColor = specularFactor.rgb;',
		].join('\n');

		var uniforms = {
			specular: { value: new Color().setHex(0xffffff) },
			glossiness: { value: 1 },
			specularMap: { value: null },
			glossinessMap: { value: null }
		};

		this._extraUniforms = uniforms;

		// please see #14031 or #13198 for an alternate approach
		this.onBeforeCompile = function (shader) {

			for (var uniformName in uniforms) {

				shader.uniforms[uniformName] = uniforms[uniformName];

			}

			shader.fragmentShader = shader.fragmentShader.replace('uniform float roughness;', 'uniform vec3 specular;');
			shader.fragmentShader = shader.fragmentShader.replace('uniform float metalness;', 'uniform float glossiness;');
			shader.fragmentShader = shader.fragmentShader.replace('#include <roughnessmap_pars_fragment>', specularMapParsFragmentChunk);
			shader.fragmentShader = shader.fragmentShader.replace('#include <metalnessmap_pars_fragment>', glossinessMapParsFragmentChunk);
			shader.fragmentShader = shader.fragmentShader.replace('#include <roughnessmap_fragment>', specularMapFragmentChunk);
			shader.fragmentShader = shader.fragmentShader.replace('#include <metalnessmap_fragment>', glossinessMapFragmentChunk);
			shader.fragmentShader = shader.fragmentShader.replace('#include <lights_physical_fragment>', lightPhysicalFragmentChunk);

		};

		/*eslint-disable*/
		Object.defineProperties(
			this,
			{
				specular: {
					get: function () { return uniforms.specular.value; },
					set: function (v) { uniforms.specular.value = v; }
				},
				specularMap: {
					get: function () { return uniforms.specularMap.value; },
					set: function (v) { uniforms.specularMap.value = v; }
				},
				glossiness: {
					get: function () { return uniforms.glossiness.value; },
					set: function (v) { uniforms.glossiness.value = v; }
				},
				glossinessMap: {
					get: function () { return uniforms.glossinessMap.value; },
					set: function (v) {

						uniforms.glossinessMap.value = v;
						//how about something like this - @pailhead
						if (v) {

							this.defines.USE_GLOSSINESSMAP = '';
							// set USE_ROUGHNESSMAP to enable vUv
							this.defines.USE_ROUGHNESSMAP = '';

						} else {

							delete this.defines.USE_ROUGHNESSMAP;
							delete this.defines.USE_GLOSSINESSMAP;

						}

					}
				}
			}
		);

		/*eslint-enable*/
		delete this.metalness;
		delete this.roughness;
		delete this.metalnessMap;
		delete this.roughnessMap;

		this.setValues(params);

	}

	GLTFMeshStandardSGMaterial.prototype = Object.create(MeshStandardMaterial.prototype);
	GLTFMeshStandardSGMaterial.prototype.constructor = GLTFMeshStandardSGMaterial;

	GLTFMeshStandardSGMaterial.prototype.copy = function (source) {

		MeshStandardMaterial.prototype.copy.call(this, source);
		this.specularMap = source.specularMap;
		this.specular.copy(source.specular);
		this.glossinessMap = source.glossinessMap;
		this.glossiness = source.glossiness;
		delete this.metalness;
		delete this.roughness;
		delete this.metalnessMap;
		delete this.roughnessMap;
		return this;

	};

	function GLTFMaterialsPbrSpecularGlossinessExtension() {

		return {

			name: EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS,

			specularGlossinessParams: [
				'color',
				'map',
				'lightMap',
				'lightMapIntensity',
				'aoMap',
				'aoMapIntensity',
				'emissive',
				'emissiveIntensity',
				'emissiveMap',
				'bumpMap',
				'bumpScale',
				'normalMap',
				'normalMapType',
				'displacementMap',
				'displacementScale',
				'displacementBias',
				'specularMap',
				'specular',
				'glossinessMap',
				'glossiness',
				'alphaMap',
				'envMap',
				'envMapIntensity',
				'refractionRatio',
			],

			getMaterialType: function () {

				return GLTFMeshStandardSGMaterial;

			},

			extendParams: function (materialParams, materialDef, parser) {

				var pbrSpecularGlossiness = materialDef.extensions[this.name];

				materialParams.color = new Color(1.0, 1.0, 1.0);
				materialParams.opacity = 1.0;

				var pending = [];

				if (Array.isArray(pbrSpecularGlossiness.diffuseFactor)) {

					var array = pbrSpecularGlossiness.diffuseFactor;

					materialParams.color.fromArray(array);
					materialParams.opacity = array[3];

				}

				if (pbrSpecularGlossiness.diffuseTexture !== undefined) {

					pending.push(parser.assignTexture(materialParams, 'map', pbrSpecularGlossiness.diffuseTexture));

				}

				materialParams.emissive = new Color(0.0, 0.0, 0.0);
				materialParams.glossiness = pbrSpecularGlossiness.glossinessFactor !== undefined ? pbrSpecularGlossiness.glossinessFactor : 1.0;
				materialParams.specular = new Color(1.0, 1.0, 1.0);

				if (Array.isArray(pbrSpecularGlossiness.specularFactor)) {

					materialParams.specular.fromArray(pbrSpecularGlossiness.specularFactor);

				}

				if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {

					var specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture;
					pending.push(parser.assignTexture(materialParams, 'glossinessMap', specGlossMapDef));
					pending.push(parser.assignTexture(materialParams, 'specularMap', specGlossMapDef));

				}

				return Promise.all(pending);

			},

			createMaterial: function (materialParams) {

				var material = new GLTFMeshStandardSGMaterial(materialParams);
				material.fog = true;

				material.color = materialParams.color;

				material.map = materialParams.map === undefined ? null : materialParams.map;

				material.lightMap = null;
				material.lightMapIntensity = 1.0;

				material.aoMap = materialParams.aoMap === undefined ? null : materialParams.aoMap;
				material.aoMapIntensity = 1.0;

				material.emissive = materialParams.emissive;
				material.emissiveIntensity = 1.0;
				material.emissiveMap = materialParams.emissiveMap === undefined ? null : materialParams.emissiveMap;

				material.bumpMap = materialParams.bumpMap === undefined ? null : materialParams.bumpMap;
				material.bumpScale = 1;

				material.normalMap = materialParams.normalMap === undefined ? null : materialParams.normalMap;
				material.normalMapType = TangentSpaceNormalMap;

				if (materialParams.normalScale) material.normalScale = materialParams.normalScale;

				material.displacementMap = null;
				material.displacementScale = 1;
				material.displacementBias = 0;

				material.specularMap = materialParams.specularMap === undefined ? null : materialParams.specularMap;
				material.specular = materialParams.specular;

				material.glossinessMap = materialParams.glossinessMap === undefined ? null : materialParams.glossinessMap;
				material.glossiness = materialParams.glossiness;

				material.alphaMap = null;

				material.envMap = materialParams.envMap === undefined ? null : materialParams.envMap;
				material.envMapIntensity = 1.0;

				material.refractionRatio = 0.98;

				return material;

			},

		};

	}

	/**
	 * Mesh Quantization Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
	 */
	function GLTFMeshQuantizationExtension() {

		this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;

	}

	/*********************************/
	/********** INTERPOLATION ********/
	/*********************************/

	// Spline Interpolation
	// Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
	function GLTFCubicSplineInterpolant(parameterPositions, sampleValues, sampleSize, resultBuffer) {

		Interpolant.call(this, parameterPositions, sampleValues, sampleSize, resultBuffer);

	}

	GLTFCubicSplineInterpolant.prototype = Object.create(Interpolant.prototype);
	GLTFCubicSplineInterpolant.prototype.constructor = GLTFCubicSplineInterpolant;

	GLTFCubicSplineInterpolant.prototype.copySampleValue_ = function (index) {

		// Copies a sample value to the result buffer. See description of glTF
		// CUBICSPLINE values layout in interpolate_() function below.

		var result = this.resultBuffer,
			values = this.sampleValues,
			valueSize = this.valueSize,
			offset = index * valueSize * 3 + valueSize;

		for (var i = 0; i !== valueSize; i++) {

			result[i] = values[offset + i];

		}

		return result;

	};

	GLTFCubicSplineInterpolant.prototype.beforeStart_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;

	GLTFCubicSplineInterpolant.prototype.afterEnd_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;

	GLTFCubicSplineInterpolant.prototype.interpolate_ = function (i1, t0, t, t1) {

		var result = this.resultBuffer;
		var values = this.sampleValues;
		var stride = this.valueSize;

		var stride2 = stride * 2;
		var stride3 = stride * 3;

		var td = t1 - t0;

		var p = (t - t0) / td;
		var pp = p * p;
		var ppp = pp * p;

		var offset1 = i1 * stride3;
		var offset0 = offset1 - stride3;

		var s2 = - 2 * ppp + 3 * pp;
		var s3 = ppp - pp;
		var s0 = 1 - s2;
		var s1 = s3 - pp + p;

		// Layout of keyframe output values for CUBICSPLINE animations:
		//   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
		for (var i = 0; i !== stride; i++) {

			var p0 = values[offset0 + i + stride]; // splineVertex_k
			var m0 = values[offset0 + i + stride2] * td; // outTangent_k * (t_k+1 - t_k)
			var p1 = values[offset1 + i + stride]; // splineVertex_k+1
			var m1 = values[offset1 + i] * td; // inTangent_k+1 * (t_k+1 - t_k)

			result[i] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;

		}

		return result;

	};

	/*********************************/
	/********** INTERNALS ************/
	/*********************************/

	/* CONSTANTS */

	var WEBGL_CONSTANTS = {
		FLOAT: 5126,
		//FLOAT_MAT2: 35674,
		FLOAT_MAT3: 35675,
		FLOAT_MAT4: 35676,
		FLOAT_VEC2: 35664,
		FLOAT_VEC3: 35665,
		FLOAT_VEC4: 35666,
		LINEAR: 9729,
		REPEAT: 10497,
		SAMPLER_2D: 35678,
		POINTS: 0,
		LINES: 1,
		LINE_LOOP: 2,
		LINE_STRIP: 3,
		TRIANGLES: 4,
		TRIANGLE_STRIP: 5,
		TRIANGLE_FAN: 6,
		UNSIGNED_BYTE: 5121,
		UNSIGNED_SHORT: 5123
	};

	var WEBGL_COMPONENT_TYPES = {
		5120: Int8Array,
		5121: Uint8Array,
		5122: Int16Array,
		5123: Uint16Array,
		5125: Uint32Array,
		5126: Float32Array
	};

	var WEBGL_FILTERS = {
		9728: NearestFilter,
		9729: LinearFilter,
		9984: NearestMipmapNearestFilter,
		9985: LinearMipmapNearestFilter,
		9986: NearestMipmapLinearFilter,
		9987: LinearMipmapLinearFilter
	};

	var WEBGL_WRAPPINGS = {
		33071: ClampToEdgeWrapping,
		33648: MirroredRepeatWrapping,
		10497: RepeatWrapping
	};

	var WEBGL_TYPE_SIZES = {
		'SCALAR': 1,
		'VEC2': 2,
		'VEC3': 3,
		'VEC4': 4,
		'MAT2': 4,
		'MAT3': 9,
		'MAT4': 16
	};

	var ATTRIBUTES = {
		POSITION: 'position',
		NORMAL: 'normal',
		TANGENT: 'tangent',
		TEXCOORD_0: 'uv',
		TEXCOORD_1: 'uv2',
		COLOR_0: 'color',
		WEIGHTS_0: 'skinWeight',
		JOINTS_0: 'skinIndex',
	};

	var PATH_PROPERTIES = {
		scale: 'scale',
		translation: 'position',
		rotation: 'quaternion',
		weights: 'morphTargetInfluences'
	};

	var INTERPOLATION = {
		CUBICSPLINE: undefined, // We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
		// keyframe track will be initialized with a default interpolation type, then modified.
		LINEAR: InterpolateLinear,
		STEP: InterpolateDiscrete
	};

	var ALPHA_MODES = {
		OPAQUE: 'OPAQUE',
		MASK: 'MASK',
		BLEND: 'BLEND'
	};

	var MIME_TYPE_FORMATS = {
		'image/png': RGBAFormat,
		'image/jpeg': RGBFormat
	};

	/* UTILITY FUNCTIONS */

	function resolveURL(url, path) {

		// Invalid URL
		if (typeof url !== 'string' || url === '') return '';

		// Host Relative URL
		if (/^https?:\/\//i.test(path) && /^\//.test(url)) {

			path = path.replace(/(^https?:\/\/[^\/]+).*/i, '$1');

		}

		// Absolute URL http://,https://,//
		if (/^(https?:)?\/\//i.test(url)) return url;

		// Data URI
		if (/^data:.*,.*$/i.test(url)) return url;

		// Blob URL
		if (/^blob:.*$/i.test(url)) return url;

		// Relative URL
		return path + url;

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
	 */
	function createDefaultMaterial(cache) {

		if (cache['DefaultMaterial'] === undefined) {

			cache['DefaultMaterial'] = new MeshStandardMaterial({
				color: 0xFFFFFF,
				emissive: 0x000000,
				metalness: 1,
				roughness: 1,
				transparent: false,
				depthTest: true,
				side: FrontSide
			});

		}

		return cache['DefaultMaterial'];

	}

	function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {

		// Add unknown glTF extensions to an object's userData.

		for (var name in objectDef.extensions) {

			if (knownExtensions[name] === undefined) {

				object.userData.gltfExtensions = object.userData.gltfExtensions || {};
				object.userData.gltfExtensions[name] = objectDef.extensions[name];

			}

		}

	}

	/**
	 * @param {Object3D|Material|BufferGeometry} object
	 * @param {GLTF.definition} gltfDef
	 */
	function assignExtrasToUserData(object, gltfDef) {

		if (gltfDef.extras !== undefined) {

			if (typeof gltfDef.extras === 'object') {

				Object.assign(object.userData, gltfDef.extras);

			} else {

				console.warn('THREE.GLTFLoader: Ignoring primitive type .extras, ' + gltfDef.extras);

			}

		}

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
	 *
	 * @param {BufferGeometry} geometry
	 * @param {Array<GLTF.Target>} targets
	 * @param {GLTFParser} parser
	 * @return {Promise<BufferGeometry>}
	 */
	function addMorphTargets(geometry, targets, parser) {

		var hasMorphPosition = false;
		var hasMorphNormal = false;

		for (var i = 0, il = targets.length; i < il; i++) {

			var target = targets[i];

			if (target.POSITION !== undefined) hasMorphPosition = true;
			if (target.NORMAL !== undefined) hasMorphNormal = true;

			if (hasMorphPosition && hasMorphNormal) break;

		}

		if (!hasMorphPosition && !hasMorphNormal) return Promise.resolve(geometry);

		var pendingPositionAccessors = [];
		var pendingNormalAccessors = [];

		for (var i = 0, il = targets.length; i < il; i++) {

			var target = targets[i];

			if (hasMorphPosition) {

				var pendingAccessor = target.POSITION !== undefined
					? parser.getDependency('accessor', target.POSITION)
					: geometry.attributes.position;

				pendingPositionAccessors.push(pendingAccessor);

			}

			if (hasMorphNormal) {

				var pendingAccessor = target.NORMAL !== undefined
					? parser.getDependency('accessor', target.NORMAL)
					: geometry.attributes.normal;

				pendingNormalAccessors.push(pendingAccessor);

			}

		}

		return Promise.all([
			Promise.all(pendingPositionAccessors),
			Promise.all(pendingNormalAccessors)
		]).then(function (accessors) {

			var morphPositions = accessors[0];
			var morphNormals = accessors[1];

			if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
			if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;
			geometry.morphTargetsRelative = true;

			return geometry;

		});

	}

	/**
	 * @param {Mesh} mesh
	 * @param {GLTF.Mesh} meshDef
	 */
	function updateMorphTargets(mesh, meshDef) {

		mesh.updateMorphTargets();

		if (meshDef.weights !== undefined) {

			for (var i = 0, il = meshDef.weights.length; i < il; i++) {

				mesh.morphTargetInfluences[i] = meshDef.weights[i];

			}

		}

		// .extras has user-defined data, so check that .extras.targetNames is an array.
		if (meshDef.extras && Array.isArray(meshDef.extras.targetNames)) {

			var targetNames = meshDef.extras.targetNames;

			if (mesh.morphTargetInfluences.length === targetNames.length) {

				mesh.morphTargetDictionary = {};

				for (var i = 0, il = targetNames.length; i < il; i++) {

					mesh.morphTargetDictionary[targetNames[i]] = i;

				}

			} else {

				console.warn('THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.');

			}

		}

	}

	function createPrimitiveKey(primitiveDef) {

		var dracoExtension = primitiveDef.extensions && primitiveDef.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION];
		var geometryKey;

		if (dracoExtension) {

			geometryKey = 'draco:' + dracoExtension.bufferView
				+ ':' + dracoExtension.indices
				+ ':' + createAttributesKey(dracoExtension.attributes);

		} else {

			geometryKey = primitiveDef.indices + ':' + createAttributesKey(primitiveDef.attributes) + ':' + primitiveDef.mode;

		}

		return geometryKey;

	}

	function createAttributesKey(attributes) {

		var attributesKey = '';

		var keys = Object.keys(attributes).sort();

		for (var i = 0, il = keys.length; i < il; i++) {

			attributesKey += keys[i] + ':' + attributes[keys[i]] + ';';

		}

		return attributesKey;

	}

	/* GLTF PARSER */

	function GLTFParser(json, extensions, options) {

		this.json = json || {};
		this.extensions = extensions || {};
		this.options = options || {};

		// loader object cache
		this.cache = new GLTFRegistry();

		// associations between Three.js objects and glTF elements
		this.associations = new Map();

		// BufferGeometry caching
		this.primitiveCache = {};

		this.textureLoader = new TextureLoader(this.options.manager);
		this.textureLoader.setCrossOrigin(this.options.crossOrigin);

		this.fileLoader = new FileLoader(this.options.manager);
		this.fileLoader.setResponseType('arraybuffer');

		if (this.options.crossOrigin === 'use-credentials') {

			this.fileLoader.setWithCredentials(true);

		}

	}

	GLTFParser.prototype.parse = function (onLoad, onError) {

		var parser = this;
		var json = this.json;
		var extensions = this.extensions;

		// Clear the loader cache
		this.cache.removeAll();

		// Mark the special nodes/meshes in json for efficient parse
		this.markDefs();

		Promise.all([

			this.getDependencies('scene'),
			this.getDependencies('animation'),
			this.getDependencies('camera'),

		]).then(function (dependencies) {

			var result = {
				scene: dependencies[0][json.scene || 0],
				scenes: dependencies[0],
				animations: dependencies[1],
				cameras: dependencies[2],
				asset: json.asset,
				parser: parser,
				userData: {}
			};

			addUnknownExtensionsToUserData(extensions, result, json);

			assignExtrasToUserData(result, json);

			onLoad(result);

		}).catch(onError);

	};

	/**
	 * Marks the special nodes/meshes in json for efficient parse.
	 */
	GLTFParser.prototype.markDefs = function () {

		var nodeDefs = this.json.nodes || [];
		var skinDefs = this.json.skins || [];
		var meshDefs = this.json.meshes || [];

		var meshReferences = {};
		var meshUses = {};

		// Nothing in the node definition indicates whether it is a Bone or an
		// Object3D. Use the skins' joint references to mark bones.
		for (var skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex++) {

			var joints = skinDefs[skinIndex].joints;

			for (var i = 0, il = joints.length; i < il; i++) {

				nodeDefs[joints[i]].isBone = true;

			}

		}

		// Meshes can (and should) be reused by multiple nodes in a glTF asset. To
		// avoid having more than one Mesh with the same name, count
		// references and rename instances below.
		//
		// Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
		for (var nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {

			var nodeDef = nodeDefs[nodeIndex];

			if (nodeDef.mesh !== undefined) {

				if (meshReferences[nodeDef.mesh] === undefined) {

					meshReferences[nodeDef.mesh] = meshUses[nodeDef.mesh] = 0;

				}

				meshReferences[nodeDef.mesh]++;

				// Nothing in the mesh definition indicates whether it is
				// a SkinnedMesh or Mesh. Use the node's mesh reference
				// to mark SkinnedMesh if node has skin.
				if (nodeDef.skin !== undefined) {

					meshDefs[nodeDef.mesh].isSkinnedMesh = true;

				}

			}

		}

		this.json.meshReferences = meshReferences;
		this.json.meshUses = meshUses;

	};

	/**
	 * Requests the specified dependency asynchronously, with caching.
	 * @param {string} type
	 * @param {number} index
	 * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
	 */
	GLTFParser.prototype.getDependency = function (type, index) {

		var cacheKey = type + ':' + index;
		var dependency = this.cache.get(cacheKey);

		if (!dependency) {

			switch (type) {

				case 'scene':
					dependency = this.loadScene(index);
					break;

				case 'node':
					dependency = this.loadNode(index);
					break;

				case 'mesh':
					dependency = this.loadMesh(index);
					break;

				case 'accessor':
					dependency = this.loadAccessor(index);
					break;

				case 'bufferView':
					dependency = this.loadBufferView(index);
					break;

				case 'buffer':
					dependency = this.loadBuffer(index);
					break;

				case 'material':
					dependency = this.loadMaterial(index);
					break;

				case 'texture':
					dependency = this.loadTexture(index);
					break;

				case 'skin':
					dependency = this.loadSkin(index);
					break;

				case 'animation':
					dependency = this.loadAnimation(index);
					break;

				case 'camera':
					dependency = this.loadCamera(index);
					break;

				case 'light':
					dependency = this.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL].loadLight(index);
					break;

				default:
					throw new Error('Unknown type: ' + type);

			}

			this.cache.add(cacheKey, dependency);

		}

		return dependency;

	};

	/**
	 * Requests all dependencies of the specified type asynchronously, with caching.
	 * @param {string} type
	 * @return {Promise<Array<Object>>}
	 */
	GLTFParser.prototype.getDependencies = function (type) {

		var dependencies = this.cache.get(type);

		if (!dependencies) {

			var parser = this;
			var defs = this.json[type + (type === 'mesh' ? 'es' : 's')] || [];

			dependencies = Promise.all(defs.map(function (def, index) {

				return parser.getDependency(type, index);

			}));

			this.cache.add(type, dependencies);

		}

		return dependencies;

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferIndex
	 * @return {Promise<ArrayBuffer>}
	 */
	GLTFParser.prototype.loadBuffer = function (bufferIndex) {

		var bufferDef = this.json.buffers[bufferIndex];
		var loader = this.fileLoader;

		if (bufferDef.type && bufferDef.type !== 'arraybuffer') {

			throw new Error('THREE.GLTFLoader: ' + bufferDef.type + ' buffer type is not supported.');

		}

		// If present, GLB container is required to be the first buffer.
		if (bufferDef.uri === undefined && bufferIndex === 0) {

			return Promise.resolve(this.extensions[EXTENSIONS.KHR_BINARY_GLTF].body);

		}

		var options = this.options;

		return new Promise(function (resolve, reject) {

			loader.load(resolveURL(bufferDef.uri, options.path), resolve, undefined, function () {

				reject(new Error('THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".'));

			});

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferViewIndex
	 * @return {Promise<ArrayBuffer>}
	 */
	GLTFParser.prototype.loadBufferView = function (bufferViewIndex) {

		var bufferViewDef = this.json.bufferViews[bufferViewIndex];

		return this.getDependency('buffer', bufferViewDef.buffer).then(function (buffer) {

			var byteLength = bufferViewDef.byteLength || 0;
			var byteOffset = bufferViewDef.byteOffset || 0;
			return buffer.slice(byteOffset, byteOffset + byteLength);

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
	 * @param {number} accessorIndex
	 * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
	 */
	GLTFParser.prototype.loadAccessor = function (accessorIndex) {

		var parser = this;
		var json = this.json;

		var accessorDef = this.json.accessors[accessorIndex];

		if (accessorDef.bufferView === undefined && accessorDef.sparse === undefined) {

			// Ignore empty accessors, which may be used to declare runtime
			// information about attributes coming from another source (e.g. Draco
			// compression extension).
			return Promise.resolve(null);

		}

		var pendingBufferViews = [];

		if (accessorDef.bufferView !== undefined) {

			pendingBufferViews.push(this.getDependency('bufferView', accessorDef.bufferView));

		} else {

			pendingBufferViews.push(null);

		}

		if (accessorDef.sparse !== undefined) {

			pendingBufferViews.push(this.getDependency('bufferView', accessorDef.sparse.indices.bufferView));
			pendingBufferViews.push(this.getDependency('bufferView', accessorDef.sparse.values.bufferView));

		}

		return Promise.all(pendingBufferViews).then(function (bufferViews) {

			var bufferView = bufferViews[0];

			var itemSize = WEBGL_TYPE_SIZES[accessorDef.type];
			var TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

			// For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
			var elementBytes = TypedArray.BYTES_PER_ELEMENT;
			var itemBytes = elementBytes * itemSize;
			var byteOffset = accessorDef.byteOffset || 0;
			var byteStride = accessorDef.bufferView !== undefined ? json.bufferViews[accessorDef.bufferView].byteStride : undefined;
			var normalized = accessorDef.normalized === true;
			var array, bufferAttribute;

			// The buffer is not interleaved if the stride is the item size in bytes.
			if (byteStride && byteStride !== itemBytes) {

				// Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own InterleavedBuffer
				// This makes sure that IBA.count reflects accessor.count properly
				var ibSlice = Math.floor(byteOffset / byteStride);
				var ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType + ':' + ibSlice + ':' + accessorDef.count;
				var ib = parser.cache.get(ibCacheKey);

				if (!ib) {

					array = new TypedArray(bufferView, ibSlice * byteStride, accessorDef.count * byteStride / elementBytes);

					// Integer parameters to IB/IBA are in array elements, not bytes.
					ib = new InterleavedBuffer(array, byteStride / elementBytes);

					parser.cache.add(ibCacheKey, ib);

				}

				bufferAttribute = new InterleavedBufferAttribute(ib, itemSize, (byteOffset % byteStride) / elementBytes, normalized);

			} else {

				if (bufferView === null) {

					array = new TypedArray(accessorDef.count * itemSize);

				} else {

					array = new TypedArray(bufferView, byteOffset, accessorDef.count * itemSize);

				}

				bufferAttribute = new BufferAttribute(array, itemSize, normalized);

			}

			// https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
			if (accessorDef.sparse !== undefined) {

				var itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
				var TypedArrayIndices = WEBGL_COMPONENT_TYPES[accessorDef.sparse.indices.componentType];

				var byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
				var byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;

				var sparseIndices = new TypedArrayIndices(bufferViews[1], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices);
				var sparseValues = new TypedArray(bufferViews[2], byteOffsetValues, accessorDef.sparse.count * itemSize);

				if (bufferView !== null) {

					// Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
					bufferAttribute = new BufferAttribute(bufferAttribute.array.slice(), bufferAttribute.itemSize, bufferAttribute.normalized);

				}

				for (var i = 0, il = sparseIndices.length; i < il; i++) {

					var index = sparseIndices[i];

					bufferAttribute.setX(index, sparseValues[i * itemSize]);
					if (itemSize >= 2) bufferAttribute.setY(index, sparseValues[i * itemSize + 1]);
					if (itemSize >= 3) bufferAttribute.setZ(index, sparseValues[i * itemSize + 2]);
					if (itemSize >= 4) bufferAttribute.setW(index, sparseValues[i * itemSize + 3]);
					if (itemSize >= 5) throw new Error('THREE.GLTFLoader: Unsupported itemSize in sparse BufferAttribute.');

				}

			}

			return bufferAttribute;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
	 * @param {number} textureIndex
	 * @return {Promise<THREE.Texture>}
	 */
	GLTFParser.prototype.loadTexture = function (textureIndex) {

		var parser = this;
		var json = this.json;
		var options = this.options;
		var textureLoader = this.textureLoader;

		var URL = self.URL || self.webkitURL;

		var textureDef = json.textures[textureIndex];

		var textureExtensions = textureDef.extensions || {};

		var source;

		if (textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]) {

			source = json.images[textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS].source];

		} else {

			source = json.images[textureDef.source];

		}

		var sourceURI = source.uri;
		var isObjectURL = false;

		if (source.bufferView !== undefined) {

			// Load binary image data from bufferView, if provided.

			sourceURI = parser.getDependency('bufferView', source.bufferView).then(function (bufferView) {

				isObjectURL = true;
				var blob = new Blob([bufferView], { type: source.mimeType });
				sourceURI = URL.createObjectURL(blob);
				return sourceURI;

			});

		}

		return Promise.resolve(sourceURI).then(function (sourceURI) {

			// Load Texture resource.

			var loader = options.manager.getHandler(sourceURI);

			if (!loader) {

				loader = textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]
					? parser.extensions[EXTENSIONS.MSFT_TEXTURE_DDS].ddsLoader
					: textureLoader;

			}

			return new Promise(function (resolve, reject) {

				loader.load(resolveURL(sourceURI, options.path), resolve, undefined, reject);

			});

		}).then(function (texture) {

			// Clean up resources and configure Texture.

			if (isObjectURL === true) {

				URL.revokeObjectURL(sourceURI);

			}

			texture.flipY = false;

			if (textureDef.name) texture.name = textureDef.name;

			// Ignore unknown mime types, like DDS files.
			if (source.mimeType in MIME_TYPE_FORMATS) {

				texture.format = MIME_TYPE_FORMATS[source.mimeType];

			}

			var samplers = json.samplers || {};
			var sampler = samplers[textureDef.sampler] || {};

			texture.magFilter = WEBGL_FILTERS[sampler.magFilter] || LinearFilter;
			texture.minFilter = WEBGL_FILTERS[sampler.minFilter] || LinearMipmapLinearFilter;
			texture.wrapS = WEBGL_WRAPPINGS[sampler.wrapS] || RepeatWrapping;
			texture.wrapT = WEBGL_WRAPPINGS[sampler.wrapT] || RepeatWrapping;

			parser.associations.set(texture, {
				type: 'textures',
				index: textureIndex
			});

			return texture;

		});

	};

	/**
	 * Asynchronously assigns a texture to the given material parameters.
	 * @param {Object} materialParams
	 * @param {string} mapName
	 * @param {Object} mapDef
	 * @return {Promise}
	 */
	GLTFParser.prototype.assignTexture = function (materialParams, mapName, mapDef) {

		var parser = this;

		return this.getDependency('texture', mapDef.index).then(function (texture) {

			if (!texture.isCompressedTexture) {

				switch (mapName) {

					case 'aoMap':
					case 'emissiveMap':
					case 'metalnessMap':
					case 'normalMap':
					case 'roughnessMap':
						texture.format = RGBFormat;
						break;

				}

			}

			// Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
			// However, we will copy UV set 0 to UV set 1 on demand for aoMap
			if (mapDef.texCoord !== undefined && mapDef.texCoord != 0 && !(mapName === 'aoMap' && mapDef.texCoord == 1)) {

				console.warn('THREE.GLTFLoader: Custom UV set ' + mapDef.texCoord + ' for texture ' + mapName + ' not yet supported.');

			}

			if (parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]) {

				var transform = mapDef.extensions !== undefined ? mapDef.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM] : undefined;

				if (transform) {

					var gltfReference = this.associations.get(texture);
					texture = parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM].extendTexture(texture, transform);
					this.associations.set(texture, gltfReference);

				}

			}

			materialParams[mapName] = texture;

		});

	};

	/**
	 * Assigns final material to a Mesh, Line, or Points instance. The instance
	 * already has a material (generated from the glTF material options alone)
	 * but reuse of the same glTF material may require multiple threejs materials
	 * to accomodate different primitive types, defines, etc. New materials will
	 * be created if necessary, and reused from a cache.
	 * @param  {Object3D} mesh Mesh, Line, or Points instance.
	 */
	GLTFParser.prototype.assignFinalMaterial = function (mesh) {

		var geometry = mesh.geometry;
		var material = mesh.material;

		var useVertexTangents = geometry.attributes.tangent !== undefined;
		var useVertexColors = geometry.attributes.color !== undefined;
		var useFlatShading = geometry.attributes.normal === undefined;
		var useSkinning = mesh.isSkinnedMesh === true;
		var useMorphTargets = Object.keys(geometry.morphAttributes).length > 0;
		var useMorphNormals = useMorphTargets && geometry.morphAttributes.normal !== undefined;

		if (mesh.isPoints) {

			var cacheKey = 'PointsMaterial:' + material.uuid;

			var pointsMaterial = this.cache.get(cacheKey);

			if (!pointsMaterial) {

				pointsMaterial = new PointsMaterial();
				Material.prototype.copy.call(pointsMaterial, material);
				pointsMaterial.color.copy(material.color);
				pointsMaterial.map = material.map;
				pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px

				this.cache.add(cacheKey, pointsMaterial);

			}

			material = pointsMaterial;

		} else if (mesh.isLine) {

			var cacheKey = 'LineBasicMaterial:' + material.uuid;

			var lineMaterial = this.cache.get(cacheKey);

			if (!lineMaterial) {

				lineMaterial = new LineBasicMaterial();
				Material.prototype.copy.call(lineMaterial, material);
				lineMaterial.color.copy(material.color);

				this.cache.add(cacheKey, lineMaterial);

			}

			material = lineMaterial;

		}

		// Clone the material if it will be modified
		if (useVertexTangents || useVertexColors || useFlatShading || useSkinning || useMorphTargets) {

			var cacheKey = 'ClonedMaterial:' + material.uuid + ':';

			if (material.isGLTFSpecularGlossinessMaterial) cacheKey += 'specular-glossiness:';
			if (useSkinning) cacheKey += 'skinning:';
			if (useVertexTangents) cacheKey += 'vertex-tangents:';
			if (useVertexColors) cacheKey += 'vertex-colors:';
			if (useFlatShading) cacheKey += 'flat-shading:';
			if (useMorphTargets) cacheKey += 'morph-targets:';
			if (useMorphNormals) cacheKey += 'morph-normals:';

			var cachedMaterial = this.cache.get(cacheKey);

			if (!cachedMaterial) {

				cachedMaterial = material.clone();

				if (useSkinning) cachedMaterial.skinning = true;
				if (useVertexTangents) cachedMaterial.vertexTangents = true;
				if (useVertexColors) cachedMaterial.vertexColors = true;
				if (useFlatShading) cachedMaterial.flatShading = true;
				if (useMorphTargets) cachedMaterial.morphTargets = true;
				if (useMorphNormals) cachedMaterial.morphNormals = true;

				this.cache.add(cacheKey, cachedMaterial);

				this.associations.set(cachedMaterial, this.associations.get(material));

			}

			material = cachedMaterial;

		}

		// workarounds for mesh and geometry

		if (material.aoMap && geometry.attributes.uv2 === undefined && geometry.attributes.uv !== undefined) {

			geometry.setAttribute('uv2', geometry.attributes.uv);

		}

		// https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
		if (material.normalScale && !useVertexTangents) {

			material.normalScale.y = - material.normalScale.y;

		}

		if (material.clearcoatNormalScale && !useVertexTangents) {

			material.clearcoatNormalScale.y = - material.clearcoatNormalScale.y;

		}

		mesh.material = material;

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
	 * @param {number} materialIndex
	 * @return {Promise<Material>}
	 */
	GLTFParser.prototype.loadMaterial = function (materialIndex) {

		var parser = this;
		var json = this.json;
		var extensions = this.extensions;
		var materialDef = json.materials[materialIndex];

		var materialType;
		var materialParams = {};
		var materialExtensions = materialDef.extensions || {};

		var pending = [];

		if (materialExtensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS]) {

			var sgExtension = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS];
			materialType = sgExtension.getMaterialType();
			pending.push(sgExtension.extendParams(materialParams, materialDef, parser));

		} else if (materialExtensions[EXTENSIONS.KHR_MATERIALS_UNLIT]) {

			var kmuExtension = extensions[EXTENSIONS.KHR_MATERIALS_UNLIT];
			materialType = kmuExtension.getMaterialType();
			pending.push(kmuExtension.extendParams(materialParams, materialDef, parser));

		} else {

			// Specification:
			// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material

			materialType = MeshStandardMaterial;

			var metallicRoughness = materialDef.pbrMetallicRoughness || {};

			materialParams.color = new Color(1.0, 1.0, 1.0);
			materialParams.opacity = 1.0;

			if (Array.isArray(metallicRoughness.baseColorFactor)) {

				var array = metallicRoughness.baseColorFactor;

				materialParams.color.fromArray(array);
				materialParams.opacity = array[3];

			}

			if (metallicRoughness.baseColorTexture !== undefined) {

				pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture));

			}

			materialParams.metalness = metallicRoughness.metallicFactor !== undefined ? metallicRoughness.metallicFactor : 1.0;
			materialParams.roughness = metallicRoughness.roughnessFactor !== undefined ? metallicRoughness.roughnessFactor : 1.0;

			if (metallicRoughness.metallicRoughnessTexture !== undefined) {

				pending.push(parser.assignTexture(materialParams, 'metalnessMap', metallicRoughness.metallicRoughnessTexture));
				pending.push(parser.assignTexture(materialParams, 'roughnessMap', metallicRoughness.metallicRoughnessTexture));

			}

		}

		if (materialDef.doubleSided === true) {

			materialParams.side = DoubleSide;

		}

		var alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;

		if (alphaMode === ALPHA_MODES.BLEND) {

			materialParams.transparent = true;

			// See: https://github.com/mrdoob/three.js/issues/17706
			materialParams.depthWrite = false;

		} else {

			materialParams.transparent = false;

			if (alphaMode === ALPHA_MODES.MASK) {

				materialParams.alphaTest = materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;

			}

		}

		if (materialDef.normalTexture !== undefined && materialType !== MeshBasicMaterial) {

			pending.push(parser.assignTexture(materialParams, 'normalMap', materialDef.normalTexture));

			materialParams.normalScale = new Vector2(1, 1);

			if (materialDef.normalTexture.scale !== undefined) {

				materialParams.normalScale.set(materialDef.normalTexture.scale, materialDef.normalTexture.scale);

			}

		}

		if (materialDef.occlusionTexture !== undefined && materialType !== MeshBasicMaterial) {

			pending.push(parser.assignTexture(materialParams, 'aoMap', materialDef.occlusionTexture));

			if (materialDef.occlusionTexture.strength !== undefined) {

				materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;

			}

		}

		if (materialDef.emissiveFactor !== undefined && materialType !== MeshBasicMaterial) {

			materialParams.emissive = new Color().fromArray(materialDef.emissiveFactor);

		}

		if (materialDef.emissiveTexture !== undefined && materialType !== MeshBasicMaterial) {

			pending.push(parser.assignTexture(materialParams, 'emissiveMap', materialDef.emissiveTexture));

		}

		if (materialExtensions[EXTENSIONS.KHR_MATERIALS_CLEARCOAT]) {

			var clearcoatExtension = extensions[EXTENSIONS.KHR_MATERIALS_CLEARCOAT];
			materialType = clearcoatExtension.getMaterialType();
			pending.push(clearcoatExtension.extendParams(materialParams, { extensions: materialExtensions }, parser));

		}

		return Promise.all(pending).then(function () {

			var material;

			if (materialType === GLTFMeshStandardSGMaterial) {

				material = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].createMaterial(materialParams);

			} else {

				material = new materialType(materialParams);

			}

			if (materialDef.name) material.name = materialDef.name;

			// baseColorTexture, emissiveTexture, and specularGlossinessTexture use sRGB encoding.
			if (material.map) material.map.encoding = sRGBEncoding;
			if (material.emissiveMap) material.emissiveMap.encoding = sRGBEncoding;

			assignExtrasToUserData(material, materialDef);

			parser.associations.set(material, { type: 'materials', index: materialIndex });

			if (materialDef.extensions) addUnknownExtensionsToUserData(extensions, material, materialDef);

			return material;

		});

	};

	/**
	 * @param {BufferGeometry} geometry
	 * @param {GLTF.Primitive} primitiveDef
	 * @param {GLTFParser} parser
	 */
	function computeBounds(geometry, primitiveDef, parser) {

		var attributes = primitiveDef.attributes;

		var box = new Box3();

		if (attributes.POSITION !== undefined) {

			var accessor = parser.json.accessors[attributes.POSITION];

			var min = accessor.min;
			var max = accessor.max;

			// glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

			if (min !== undefined && max !== undefined) {

				box.set(
					new Vector3(min[0], min[1], min[2]),
					new Vector3(max[0], max[1], max[2]));

			} else {

				console.warn('THREE.GLTFLoader: Missing min/max properties for accessor POSITION.');

				return;

			}

		} else {

			return;

		}

		var targets = primitiveDef.targets;

		if (targets !== undefined) {

			var maxDisplacement = new Vector3();
			var vector = new Vector3();

			for (var i = 0, il = targets.length; i < il; i++) {

				var target = targets[i];

				if (target.POSITION !== undefined) {

					var accessor = parser.json.accessors[target.POSITION];
					var min = accessor.min;
					var max = accessor.max;

					// glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

					if (min !== undefined && max !== undefined) {

						// we need to get max of absolute components because target weight is [-1,1]
						vector.setX(Math.max(Math.abs(min[0]), Math.abs(max[0])));
						vector.setY(Math.max(Math.abs(min[1]), Math.abs(max[1])));
						vector.setZ(Math.max(Math.abs(min[2]), Math.abs(max[2])));

						// Note: this assumes that the sum of all weights is at most 1. This isn't quite correct - it's more conservative
						// to assume that each target can have a max weight of 1. However, for some use cases - notably, when morph targets
						// are used to implement key-frame animations and as such only two are active at a time - this results in very large
						// boxes. So for now we make a box that's sometimes a touch too small but is hopefully mostly of reasonable size.
						maxDisplacement.max(vector);

					} else {

						console.warn('THREE.GLTFLoader: Missing min/max properties for accessor POSITION.');

					}

				}

			}

			// As per comment above this box isn't conservative, but has a reasonable size for a very large number of morph targets.
			box.expandByVector(maxDisplacement);

		}

		geometry.boundingBox = box;

		var sphere = new Sphere();

		box.getCenter(sphere.center);
		sphere.radius = box.min.distanceTo(box.max) / 2;

		geometry.boundingSphere = sphere;

	}

	/**
	 * @param {BufferGeometry} geometry
	 * @param {GLTF.Primitive} primitiveDef
	 * @param {GLTFParser} parser
	 * @return {Promise<BufferGeometry>}
	 */
	function addPrimitiveAttributes(geometry, primitiveDef, parser) {

		var attributes = primitiveDef.attributes;

		var pending = [];

		function assignAttributeAccessor(accessorIndex, attributeName) {

			return parser.getDependency('accessor', accessorIndex)
				.then(function (accessor) {

					geometry.setAttribute(attributeName, accessor);

				});

		}

		for (var gltfAttributeName in attributes) {

			var threeAttributeName = ATTRIBUTES[gltfAttributeName] || gltfAttributeName.toLowerCase();

			// Skip attributes already provided by e.g. Draco extension.
			if (threeAttributeName in geometry.attributes) continue;

			pending.push(assignAttributeAccessor(attributes[gltfAttributeName], threeAttributeName));

		}

		if (primitiveDef.indices !== undefined && !geometry.index) {

			var accessor = parser.getDependency('accessor', primitiveDef.indices).then(function (accessor) {

				geometry.setIndex(accessor);

			});

			pending.push(accessor);

		}

		assignExtrasToUserData(geometry, primitiveDef);

		computeBounds(geometry, primitiveDef, parser);

		return Promise.all(pending).then(function () {

			return primitiveDef.targets !== undefined
				? addMorphTargets(geometry, primitiveDef.targets, parser)
				: geometry;

		});

	}

	/**
	 * @param {BufferGeometry} geometry
	 * @param {Number} drawMode
	 * @return {BufferGeometry}
	 */
	function toTrianglesDrawMode(geometry, drawMode) {

		var index = geometry.getIndex();

		// generate index if not present

		if (index === null) {

			var indices = [];

			var position = geometry.getAttribute('position');

			if (position !== undefined) {

				for (var i = 0; i < position.count; i++) {

					indices.push(i);

				}

				geometry.setIndex(indices);
				index = geometry.getIndex();

			} else {

				console.error('THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.');
				return geometry;

			}

		}

		//

		var numberOfTriangles = index.count - 2;
		var newIndices = [];

		if (drawMode === TriangleFanDrawMode) {

			// gl.TRIANGLE_FAN

			for (var i = 1; i <= numberOfTriangles; i++) {

				newIndices.push(index.getX(0));
				newIndices.push(index.getX(i));
				newIndices.push(index.getX(i + 1));

			}

		} else {

			// gl.TRIANGLE_STRIP

			for (var i = 0; i < numberOfTriangles; i++) {

				if (i % 2 === 0) {

					newIndices.push(index.getX(i));
					newIndices.push(index.getX(i + 1));
					newIndices.push(index.getX(i + 2));


				} else {

					newIndices.push(index.getX(i + 2));
					newIndices.push(index.getX(i + 1));
					newIndices.push(index.getX(i));

				}

			}

		}

		if ((newIndices.length / 3) !== numberOfTriangles) {

			console.error('THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.');

		}

		// build final geometry

		var newGeometry = geometry.clone();
		newGeometry.setIndex(newIndices);

		return newGeometry;

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
	 *
	 * Creates BufferGeometries from primitives.
	 *
	 * @param {Array<GLTF.Primitive>} primitives
	 * @return {Promise<Array<BufferGeometry>>}
	 */
	GLTFParser.prototype.loadGeometries = function (primitives) {

		var parser = this;
		var extensions = this.extensions;
		var cache = this.primitiveCache;

		function createDracoPrimitive(primitive) {

			return extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
				.decodePrimitive(primitive, parser)
				.then(function (geometry) {

					return addPrimitiveAttributes(geometry, primitive, parser);

				});

		}

		var pending = [];

		for (var i = 0, il = primitives.length; i < il; i++) {

			var primitive = primitives[i];
			var cacheKey = createPrimitiveKey(primitive);

			// See if we've already created this geometry
			var cached = cache[cacheKey];

			if (cached) {

				// Use the cached geometry if it exists
				pending.push(cached.promise);

			} else {

				var geometryPromise;

				if (primitive.extensions && primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]) {

					// Use DRACO geometry if available
					geometryPromise = createDracoPrimitive(primitive);

				} else {

					// Otherwise create a new geometry
					geometryPromise = addPrimitiveAttributes(new BufferGeometry(), primitive, parser);

				}

				// Cache this geometry
				cache[cacheKey] = { primitive: primitive, promise: geometryPromise };

				pending.push(geometryPromise);

			}

		}

		return Promise.all(pending);

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
	 * @param {number} meshIndex
	 * @return {Promise<Group|Mesh|SkinnedMesh>}
	 */
	GLTFParser.prototype.loadMesh = function (meshIndex) {

		var parser = this;
		var json = this.json;

		var meshDef = json.meshes[meshIndex];
		var primitives = meshDef.primitives;

		var pending = [];

		for (var i = 0, il = primitives.length; i < il; i++) {

			var material = primitives[i].material === undefined
				? createDefaultMaterial(this.cache)
				: this.getDependency('material', primitives[i].material);

			pending.push(material);

		}

		pending.push(parser.loadGeometries(primitives));

		return Promise.all(pending).then(function (results) {

			var materials = results.slice(0, results.length - 1);
			var geometries = results[results.length - 1];

			var meshes = [];

			for (var i = 0, il = geometries.length; i < il; i++) {

				var geometry = geometries[i];
				var primitive = primitives[i];

				// 1. create Mesh

				var mesh;

				var material = materials[i];

				if (primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
					primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
					primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
					primitive.mode === undefined) {

					// .isSkinnedMesh isn't in glTF spec. See .markDefs()
					mesh = meshDef.isSkinnedMesh === true
						? new SkinnedMesh(geometry, material)
						: new Mesh(geometry, material);

					if (mesh.isSkinnedMesh === true && !mesh.geometry.attributes.skinWeight.normalized) {

						// we normalize floating point skin weight array to fix malformed assets (see #15319)
						// it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
						mesh.normalizeSkinWeights();

					}

					if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {

						mesh.geometry = toTrianglesDrawMode(mesh.geometry, TriangleStripDrawMode);

					} else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {

						mesh.geometry = toTrianglesDrawMode(mesh.geometry, TriangleFanDrawMode);

					}

				} else if (primitive.mode === WEBGL_CONSTANTS.LINES) {

					mesh = new LineSegments(geometry, material);

				} else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {

					mesh = new Line(geometry, material);

				} else if (primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {

					mesh = new LineLoop(geometry, material);

				} else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {

					mesh = new Points(geometry, material);

				} else {

					throw new Error('THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode);

				}

				if (Object.keys(mesh.geometry.morphAttributes).length > 0) {

					updateMorphTargets(mesh, meshDef);

				}

				mesh.name = meshDef.name || ('mesh_' + meshIndex);

				if (geometries.length > 1) mesh.name += '_' + i;

				assignExtrasToUserData(mesh, meshDef);

				parser.assignFinalMaterial(mesh);

				meshes.push(mesh);

			}

			if (meshes.length === 1) {

				return meshes[0];

			}

			var group = new Group();

			for (var i = 0, il = meshes.length; i < il; i++) {

				group.add(meshes[i]);

			}

			return group;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
	 * @param {number} cameraIndex
	 * @return {Promise<THREE.Camera>}
	 */
	GLTFParser.prototype.loadCamera = function (cameraIndex) {

		var camera;
		var cameraDef = this.json.cameras[cameraIndex];
		var params = cameraDef[cameraDef.type];

		if (!params) {

			console.warn('THREE.GLTFLoader: Missing camera parameters.');
			return;

		}

		if (cameraDef.type === 'perspective') {

			camera = new PerspectiveCamera(MathUtils.radToDeg(params.yfov), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6);

		} else if (cameraDef.type === 'orthographic') {

			camera = new OrthographicCamera(- params.xmag, params.xmag, params.ymag, - params.ymag, params.znear, params.zfar);

		}

		if (cameraDef.name) camera.name = cameraDef.name;

		assignExtrasToUserData(camera, cameraDef);

		return Promise.resolve(camera);

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
	 * @param {number} skinIndex
	 * @return {Promise<Object>}
	 */
	GLTFParser.prototype.loadSkin = function (skinIndex) {

		var skinDef = this.json.skins[skinIndex];

		var skinEntry = { joints: skinDef.joints };

		if (skinDef.inverseBindMatrices === undefined) {

			return Promise.resolve(skinEntry);

		}

		return this.getDependency('accessor', skinDef.inverseBindMatrices).then(function (accessor) {

			skinEntry.inverseBindMatrices = accessor;

			return skinEntry;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
	 * @param {number} animationIndex
	 * @return {Promise<AnimationClip>}
	 */
	GLTFParser.prototype.loadAnimation = function (animationIndex) {

		var json = this.json;

		var animationDef = json.animations[animationIndex];

		var pendingNodes = [];
		var pendingInputAccessors = [];
		var pendingOutputAccessors = [];
		var pendingSamplers = [];
		var pendingTargets = [];

		for (var i = 0, il = animationDef.channels.length; i < il; i++) {

			var channel = animationDef.channels[i];
			var sampler = animationDef.samplers[channel.sampler];
			var target = channel.target;
			var name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.
			var input = animationDef.parameters !== undefined ? animationDef.parameters[sampler.input] : sampler.input;
			var output = animationDef.parameters !== undefined ? animationDef.parameters[sampler.output] : sampler.output;

			pendingNodes.push(this.getDependency('node', name));
			pendingInputAccessors.push(this.getDependency('accessor', input));
			pendingOutputAccessors.push(this.getDependency('accessor', output));
			pendingSamplers.push(sampler);
			pendingTargets.push(target);

		}

		return Promise.all([

			Promise.all(pendingNodes),
			Promise.all(pendingInputAccessors),
			Promise.all(pendingOutputAccessors),
			Promise.all(pendingSamplers),
			Promise.all(pendingTargets)

		]).then(function (dependencies) {

			var nodes = dependencies[0];
			var inputAccessors = dependencies[1];
			var outputAccessors = dependencies[2];
			var samplers = dependencies[3];
			var targets = dependencies[4];

			var tracks = [];

			for (var i = 0, il = nodes.length; i < il; i++) {

				var node = nodes[i];
				var inputAccessor = inputAccessors[i];
				var outputAccessor = outputAccessors[i];
				var sampler = samplers[i];
				var target = targets[i];

				if (node === undefined) continue;

				node.updateMatrix();
				node.matrixAutoUpdate = true;

				var TypedKeyframeTrack;

				switch (PATH_PROPERTIES[target.path]) {

					case PATH_PROPERTIES.weights:

						TypedKeyframeTrack = NumberKeyframeTrack;
						break;

					case PATH_PROPERTIES.rotation:

						TypedKeyframeTrack = QuaternionKeyframeTrack;
						break;

					case PATH_PROPERTIES.position:
					case PATH_PROPERTIES.scale:
					default:

						TypedKeyframeTrack = VectorKeyframeTrack;
						break;

				}

				var targetName = node.name ? node.name : node.uuid;

				var interpolation = sampler.interpolation !== undefined ? INTERPOLATION[sampler.interpolation] : InterpolateLinear;

				var targetNames = [];

				if (PATH_PROPERTIES[target.path] === PATH_PROPERTIES.weights) {

					// Node may be a Group (glTF mesh with several primitives) or a Mesh.
					node.traverse(function (object) {

						if (object.isMesh === true && object.morphTargetInfluences) {

							targetNames.push(object.name ? object.name : object.uuid);

						}

					});

				} else {

					targetNames.push(targetName);

				}

				var outputArray = outputAccessor.array;

				if (outputAccessor.normalized) {

					var scale;

					if (outputArray.constructor === Int8Array) {

						scale = 1 / 127;

					} else if (outputArray.constructor === Uint8Array) {

						scale = 1 / 255;

					} else if (outputArray.constructor == Int16Array) {

						scale = 1 / 32767;

					} else if (outputArray.constructor === Uint16Array) {

						scale = 1 / 65535;

					} else {

						throw new Error('THREE.GLTFLoader: Unsupported output accessor component type.');

					}

					var scaled = new Float32Array(outputArray.length);

					for (var j = 0, jl = outputArray.length; j < jl; j++) {

						scaled[j] = outputArray[j] * scale;

					}

					outputArray = scaled;

				}

				for (var j = 0, jl = targetNames.length; j < jl; j++) {

					var track = new TypedKeyframeTrack(
						targetNames[j] + '.' + PATH_PROPERTIES[target.path],
						inputAccessor.array,
						outputArray,
						interpolation
					);

					// Override interpolation with custom factory method.
					if (sampler.interpolation === 'CUBICSPLINE') {

						track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline(result) {

							// A CUBICSPLINE keyframe in glTF has three output values for each input value,
							// representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
							// must be divided by three to get the interpolant's sampleSize argument.

							return new GLTFCubicSplineInterpolant(this.times, this.values, this.getValueSize() / 3, result);

						};

						// Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.
						track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;

					}

					tracks.push(track);

				}

			}

			var name = animationDef.name ? animationDef.name : 'animation_' + animationIndex;

			return new AnimationClip(name, undefined, tracks);

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
	 * @param {number} nodeIndex
	 * @return {Promise<Object3D>}
	 */
	GLTFParser.prototype.loadNode = function (nodeIndex) {

		var json = this.json;
		var extensions = this.extensions;
		var parser = this;

		var meshReferences = json.meshReferences;
		var meshUses = json.meshUses;

		var nodeDef = json.nodes[nodeIndex];

		return (function () {

			var pending = [];

			if (nodeDef.mesh !== undefined) {

				pending.push(parser.getDependency('mesh', nodeDef.mesh).then(function (mesh) {

					var node;

					if (meshReferences[nodeDef.mesh] > 1) {

						var instanceNum = meshUses[nodeDef.mesh]++;

						node = mesh.clone();
						node.name += '_instance_' + instanceNum;

					} else {

						node = mesh;

					}

					// if weights are provided on the node, override weights on the mesh.
					if (nodeDef.weights !== undefined) {

						node.traverse(function (o) {

							if (!o.isMesh) return;

							for (var i = 0, il = nodeDef.weights.length; i < il; i++) {

								o.morphTargetInfluences[i] = nodeDef.weights[i];

							}

						});

					}

					return node;

				}));

			}

			if (nodeDef.camera !== undefined) {

				pending.push(parser.getDependency('camera', nodeDef.camera));

			}

			if (nodeDef.extensions
				&& nodeDef.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL]
				&& nodeDef.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL].light !== undefined) {

				pending.push(parser.getDependency('light', nodeDef.extensions[EXTENSIONS.KHR_LIGHTS_PUNCTUAL].light));

			}

			return Promise.all(pending);

		}()).then(function (objects) {

			var node;

			// .isBone isn't in glTF spec. See .markDefs
			if (nodeDef.isBone === true) {

				node = new Bone();

			} else if (objects.length > 1) {

				node = new Group();

			} else if (objects.length === 1) {

				node = objects[0];

			} else {

				node = new Object3D();

			}

			if (node !== objects[0]) {

				for (var i = 0, il = objects.length; i < il; i++) {

					node.add(objects[i]);

				}

			}

			if (nodeDef.name) {

				node.userData.name = nodeDef.name;
				node.name = PropertyBinding.sanitizeNodeName(nodeDef.name);

			}

			assignExtrasToUserData(node, nodeDef);

			if (nodeDef.extensions) addUnknownExtensionsToUserData(extensions, node, nodeDef);

			if (nodeDef.matrix !== undefined) {

				var matrix = new Matrix4();
				matrix.fromArray(nodeDef.matrix);
				node.applyMatrix4(matrix);

			} else {

				if (nodeDef.translation !== undefined) {

					node.position.fromArray(nodeDef.translation);

				}

				if (nodeDef.rotation !== undefined) {

					node.quaternion.fromArray(nodeDef.rotation);

				}

				if (nodeDef.scale !== undefined) {

					node.scale.fromArray(nodeDef.scale);

				}

			}

			parser.associations.set(node, { type: 'nodes', index: nodeIndex });

			return node;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
	 * @param {number} sceneIndex
	 * @return {Promise<Group>}
	 */
	GLTFParser.prototype.loadScene = function () {

		// scene node hierachy builder

		function buildNodeHierachy(nodeId, parentObject, json, parser) {

			var nodeDef = json.nodes[nodeId];

			return parser.getDependency('node', nodeId).then(function (node) {

				if (nodeDef.skin === undefined) return node;

				// build skeleton here as well

				var skinEntry;

				return parser.getDependency('skin', nodeDef.skin).then(function (skin) {

					skinEntry = skin;

					var pendingJoints = [];

					for (var i = 0, il = skinEntry.joints.length; i < il; i++) {

						pendingJoints.push(parser.getDependency('node', skinEntry.joints[i]));

					}

					return Promise.all(pendingJoints);

				}).then(function (jointNodes) {

					node.traverse(function (mesh) {

						if (!mesh.isMesh) return;

						var bones = [];
						var boneInverses = [];

						for (var j = 0, jl = jointNodes.length; j < jl; j++) {

							var jointNode = jointNodes[j];

							if (jointNode) {

								bones.push(jointNode);

								var mat = new Matrix4();

								if (skinEntry.inverseBindMatrices !== undefined) {

									mat.fromArray(skinEntry.inverseBindMatrices.array, j * 16);

								}

								boneInverses.push(mat);

							} else {

								console.warn('THREE.GLTFLoader: Joint "%s" could not be found.', skinEntry.joints[j]);

							}

						}

						mesh.bind(new Skeleton(bones, boneInverses), mesh.matrixWorld);

					});

					return node;

				});

			}).then(function (node) {

				// build node hierachy

				parentObject.add(node);

				var pending = [];

				if (nodeDef.children) {

					var children = nodeDef.children;

					for (var i = 0, il = children.length; i < il; i++) {

						var child = children[i];
						pending.push(buildNodeHierachy(child, node, json, parser));

					}

				}

				return Promise.all(pending);

			});

		}

		return function loadScene(sceneIndex) {

			var json = this.json;
			var extensions = this.extensions;
			var sceneDef = this.json.scenes[sceneIndex];
			var parser = this;

			// Loader returns Group, not Scene.
			// See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
			var scene = new Group();
			if (sceneDef.name) scene.name = sceneDef.name;

			assignExtrasToUserData(scene, sceneDef);

			if (sceneDef.extensions) addUnknownExtensionsToUserData(extensions, scene, sceneDef);

			var nodeIds = sceneDef.nodes || [];

			var pending = [];

			for (var i = 0, il = nodeIds.length; i < il; i++) {

				pending.push(buildNodeHierachy(nodeIds[i], scene, json, parser));

			}

			return Promise.all(pending).then(function () {

				return scene;

			});

		};

	}();

	return GLTFLoader;

})();

export { GLTFLoader };
